1. Field of the Invention
The present invention relates to methods and apparatus for correcting for non-uniformities occuring in the rotation of the drive shaft of a drive system.
2. Description of the Related Art
Especially in drive systems which have an internal combustion engine as the drive assembly, nonuniformities generally occur in the rotation of the drive shaft of the engine, which are primarily caused by the gas and mass forces of the engine. Such rotational nonuniformities can impair the driving comfort and lead to wear on the drive system, as well.
Therefore, it has already been proposed to outfit an internal combustion engine of a motor vehicle with a system for active reduction of rotational nonuniformities. The action of such a system is based on the fact that an electric machine or an electric brake generates a torque which alternates or also only pulsates in one direction, which is directed opposite the rotational nonuniformities and thereby reduces them. Examples of such systems are disclosed by Patent Abstracts of Japan, Volume 11, No. 28 (M-557), 27 Jan. 1987 & JP-A-61 200 333 (NISSAN I), Patent Abstract of Japan, Volume 4, No. 29 (M-002),14 Mar. 1980 & JP-A-55 005 454 (TOYOTA), EP-B-0 427 568 (ISUZU), DE-A-32 30 607 (VW), EP-B-0 175 952 and U.S. Pat. No. 699 097 (MAZDA), Patent Abstracts of Japan, Volume 7, No. 240 (M-251), 25 Oct. 1983 and JP-A-58 126 434 (NISSAN II), DE-A-41 00 937 (FICHTEL & SACHS), EP-A-0 604 979 (NIPPONDENSO), EP-A-0 385 311 (NISSAN/HITACHI), EP-A-0 338 485 (HITACHI) and U.S. Pat. No. 5 109 815 (HITACHI II).
The following more remote state of the art is cited: DE-B-43 91 898, DE-A-27 04 533, EP-A-0 437 266, DE-A-44 37 322, DE-A-40 11 291, DE-A-32 43 513, DE-A-38 14 484, DE-A-33 38 548, DE-B-44 08 719, DE-A-39 37 082.
In the correspondingly equipped drive systems, therefore, an active reduction of rotational nonuniformities is basically possible